1. Field of the Invention
This invention relates to a machine having a drive member and a method for diagnosing the same and, particularly relates to a method for diagnosing a machine having a drive member having functions in which damage of the drive member is monitored continuously, the damage condition is determined, and whether it is normal or not is self-diagnosed, in fabrication machines for semiconductor devices (for example, die bonders, wire bonders, or taping machines etc.) having the drive members heavily loaded by fast operation. Also, the present invention relates to a machine having such a drive member.
2. Description of the Related Art
Semiconductor dies (hereinafter called xe2x80x9cdiesxe2x80x9d) are prepared from 6xe2x80x3 or 8xe2x80x3 wafers, and then cut into rectangular shape to be formed completed product of dies. The profiles of the dies are variously different including an approximately square with one side from 0.2 mm to 30 mm, or an oblong card-like shape in some cases. The dies are positioned and adhered on leadframes one by one by the die bonder, then respective dies are wire bonded with the leads and molded, thereafter the leadframes are cut by each die to be formed completed leads. Completed product of dies after characteristic inspection is received in pockets of tape by the taping machine. Then, they are mounted on intended places of printed circuit boards by mounters. These processes are generally utilized as a latter process in fabrication of semiconductor products such as ICs, and various fabrication machines for semiconductor devices as described above are used in the process.
Hereinafter, a description will be given with reference to the die bonders as an example among those machines. The die bonder is of a machine which picks the rectangular shape-cut-die up one by one from the wafer and positions the die on a predetermined place of the leadframe. This will be described in detail using FIG. 3. FIG. 3 is a perspective view of the die bonder 1, where a pick-and-place unit 2 is drawn in center area.
The above-mentioned die bonder 1 picks the die 6 in the wafer 4 up one by one using the pick-and-place unit 2, the die being cut into grid-like pattern in a state attached to adhesive sheet 3, and positions the die on a land 8 in the leadframe 7 which advances at a constant pitch.
Cameras (not shown) are placed above the picked-up die 6 and the land 8 on which die 6 is positioned. A former camera is used for recognizing the position of the picked-up die 6 to align its position together with the adhering sheet 3. On the other hand, a latter camera is used for recognizing the position of the land 8 to correct the position of the die 6 in alignment with the recognized land position during transfer.
Therefore, it is required for the pick-and-place unit 2 to move along X-axis (right and left), as well as Y-axis (back and forth) and Z-axis (up and down). The reason of need for the motion along the X-axis is that location of the die 6 must be corrected right and left during transfer, while not shown.
As to the drive member along the Y axis, a motor 9 is provided as a driving source, and a nut 12 moves back and forth due to rotation of a ball screw 11 connected with a rotating shaft of the motor 9. A guide bar 13 is arranged parallel to the screw 11, and thus the nut 12 can move linearly without chattering.
On the other hand, an LM guide (linear moving guide) 14 is arranged on the nut 12, and a die suction head 16 moves up and down along the LM guide 14. Similarly as the above case, for this motion, a motor (not shown) is provided behind a connection bar 17 as a driving source.
Further, for the motion along the X axis in typically utilized method, while not shown as above, the whole of the shown pick-and-place unit 2 is mounted on a sliding unit movable along the X axis, and moved right and left by a motor. Therefore, the pick-and-place unit 2 typically weighs more than 5 kg.
However, there has been following problems in the above conventional die bonders.
Recently, demand for shortening the machine""s cycle time increases more and more, so a particular die bonder must be provided responding to the demand. Particularly, in faster types, cycle time of about 0.35 sec/die by the conventional one has been shortened to 0.2-0.25 sec/die. On the contrary, when the die is positioned on the land 8 of the leadframe 7, high positioning accuracy is still required. The reason is that, as the die 6 has become smaller, size margin of the land 8 relative to the size of the die 6 has been correspondingly reduced, or higher positioning accuracy is required increasingly in latter fabrication process (for example wire bonding).
Such highly accurate positioning of die 6 necessarily requires a particular structure as shown in FIG. 3. Then, the pick-and-place unit 2 must weigh heavily corresponding to the structure. When fast operation is done in this condition, mechanical driving components are loaded heavily.
Comparing accelerations along the Y axis as an example, an estimation shows that acceleration will reach to 20 G at a shortened cycle time of 0.2-0.25 sec/die, while it is about 5 G at a prior art cycle time of about 0.35 sec/die.
If the die bonder 1 is continued to be driven under such conditions, the fast driving components (particularly the ball screw or the LM guide) fail soon, resulting in difficulty of normal operation. Once a failure occurs, there are no recovery means except replacement of components. However, in some cases, several days are required for retrieving the bonder after the replacement. Furthermore, this procedure is merely a post-symptomatic-treatment, because failure could not be predicted.
As counter measures to solve these problems, following means have been tried.
If the components have abraded, or original assembly condition was inadequate, chattering or galling may occur in the drive member. It arises as certain vibration having a certain characteristic frequency. Therefore, sensors for detecting the vibration are installed in the drive member so that variation of the vibration can be monitored with the sensors.
However, in this method, the sensors must be installed for a number of the drive members respectively. In frequently used method, amplitude of the vibration is processed and analyzed with FFT (Fast Fourier Transformation), however, in this case FFT analyzer and PC must be connected to the die bonder 1 for each analysis. These requirements cause rise of fabrication cost, complicated structure of the die bonder 1 itself, and troublesome operation for analysis.
Moreover, spans, in which failures occurred, were different for respective die bonders 1 or driven regions, and thus not uniform. As a result, in case analysis was performed in a particular span equally for respective die bonders 1, failure of the drive member could not be found before operation.
Therefore, there is a need for development of a novel die bonder, which can recognize the damage condition of the fast driving components at any time and take a best response based on the condition, even at fast operation. At the same time, there is a need for that each component of the drive member can be assembled under the best condition when the die bonder is assembled, and life of the die bonder is prolonged as long as possible thereby.
It is clear that similar problems exist and must be solved in fabrication machines other than the die bonder as described in beginning, relating to a current demand for faster operation.
Therefore, in order to solve the above problems, the present invention provides a method for diagnosing a machine having a drive member and the machine, particularly a method for diagnosing a fabrication machine for a semiconductor device and the machine.
A first feature of the present invention is a method for diagnosing a machine having a drive member, the machine having: the drive member moved linearly or rotationally; a motor as a driving source for the drive member; a motor controller for outputting a driving signal to the motor and receiving a current location data signal from the motor; and a machine controller for controlling the entire machine, the method including the steps of creating vibration information of the drive member from the driving signal and the current location data signal by the motor controller; sending the vibration information of the drive member from the motor controller to the machine controller; and diagnosing whether a driving condition of the drive member is normal or not in the machine controller by comparing the vibration information of the drive member with reference vibration information.
A second feature of the invention is the method for diagnosing a machine having a drive member, in which the reference vibration information of the drive member, vibration information at beginning of operation of the drive member, and vibration information during respective fixed periods after beginning of operation are stored in the machine controller; the vibration information at beginning of operation of the drive member and/or the vibration information during each fixed period after beginning of operation is compared with the reference vibration information of the drive member to diagnose whether the driving condition of the drive member is normal or not in the machine controller.
A third feature of the invention is the method for diagnosing a machine having a drive member, in which the reference vibration information of the drive member is set based on a standard abrasion characteristic of the drive member accompanied with time passing after beginning of operation of the drive member.
A fourth feature of the invention is the method for diagnosing a machine having a drive member, in which the vibration information during respective fixed periods after beginning of operation are stored over multiple periods, and vibration information during the latest fixed period is substituted for the stored vibration information during the oldest fixed period sequentially.
A fifth feature of the invention is the method for diagnosing a machine having a drive member, in which the reference vibration information of the drive member, the vibration information at beginning of operation of the drive member, and the vibration information during respective fixed periods after beginning of operation are indicated as a characteristic frequency of the drive member.
A sixth feature of the invention is a machine having a drive member, which includes the drive member moved linearly or rotationally; a motor as a driving source for the drive member; a motor controller for outputting a driving signal to the motor and receiving a current location data signal from the motor; and a machine controller for controlling the entire machine, vibration information of the drive member being created from the driving signal and the current location data signal in the motor controller, the vibration information of the drive member being sent from the motor controller to the machine controller, the machine controller being provided with an information storage for storing the vibration information of the drive member, an operational processor for operating the stored information, and a display unit for displaying a condition of the drive member according to operation results.
A seventh feature of the invention is the machine having a drive member, in which the information storage includes an initial information storage area for storing initial vibration information of the drive member; and period information storage areas for storing vibration information of the drive member during a fixed period, the operational processor operationally compares the initial vibration information of the drive member stored in the initial information storage area with the vibration information of the drive member stored in the multiple period information storage areas, and a condition of the drive member is displayed on the display unit according to operation results.
An eighth feature of the invention is the machine having a drive member, in which the vibration information of the drive member during the fixed time period is transferred among the multiple period information storage areas by turns, and the vibration information of the drive member during the oldest fixed period is deleted by turns.
A ninth feature of the invention is the machine having a drive member, in which the drive member constitutes at least a part of a fabrication machine for a semiconductor device.
The nature, principle, and utility of the invention will become more apparent from the following detailed description when read in conjunction with the accompanying drawings in which like parts are designated by like reference numerals or characters.